A novel microbial sensor for the determination of cyanide

A novel cyanide biosensor was developed using cyanide-degrading microorganisms immobilized in membrane and an oxygen electrode. Immobilized Pseudomonas fluorescens NCIMB 11764 specifically oxidized cyanide thereby consuming oxygen without reacting with other toxic materials (like Cr3+, Cd2+, Pb2+, LAS). A change in oxygen concentration was detected using a Clark oxygen electrode. Cyanide could thus be determined at concentrations between 0.1 and 1 ppm in 50 mM phosphate buffer (pH 8). The optimum working conditions of the sensor are pH 8 at 30 °C, resulting in a response time of less than 2 min. This sensor was unaffected by chloride and heavy-metal ions. The relative standard deviation was estimated to be about 8%. With its specificity, rapid response time and ease of operation, this cyanide sensor has a potential commercial application for the monitoring and sensing of cyanide in industrial wastes.